Autoimmunity
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Autoimmunity is a condition where the body's immune system mistakenly attacks its own cells, leading to various autoimmune diseases classified as organ-specific or systemic. Common examples include type 1 diabetes, systemic lupus erythematosus, and Hashimoto's thyroiditis, each with distinct effects on the body. Factors contributing to autoimmunity include hidden antigens, molecular changes in tissues, and molecular mimicry from infectious agents.
Autoimmunity
- 2. Autoimmunity • Body declares war on itself • refers to a failure of the body’s immune system to recognize its own cells and tissues as “self”. • Instead, immune responses are launched against these cells and tissues as if they were foreign or invading bodies. • is a condition in which the body produces antibodies and T cell responses against elements of its own tissues (autoantigens). • the state in which the immune system reacts against the body’s own normal components, producing disease or functional changes.
- 3. Types of autoimmune diseases • Divided into two classes: • organ-specific and systemic. • An organ-specific disease is one in which an immune response is directed toward antigens in a single organ. • Examples are Addison disease, in which autoantibodies attack the adrenal cortex, and myasthenia gravis, in which they attack neuromuscular cells. • In systemic diseases the immune system attacks self antigens in several organs. • Systemic lupus erythematosus, for example, is characterized by inflammation of the skin, joints, and kidneys, among other organs.
- 4. Causes of autoimmune disease • Antigen hidden or sequestrated in cells or tissues • Some body proteins remain hidden or sequestrated from immunologically competent cells. So, they are not recognized as ‘self’ by the immune system. • When such protein escape into the circulation (due to trauma or infection), they behave as antigens, induce immune response and produce tissue damage. • Examples: • Lens protein: usually isolated or sequestrated from immune system during development. Due to trauma to the eye, lens protein may escape into circulation, produce autoantibody and cause immunologic damage to the eye (sympathetic ophthalmia).
- 5. Causes of autoimmune disease • Antigen formed by molecular changes • Body tissues or cells undergo antigenic alteration due to physical, chemical or biological influences. Such neoantigen elicit immune response. • Examples: • Immunoconglutinins(IKs): IKs are antoantobodies produced against complement components like C2, C3 and C4. • The new epitopes are exposed during complement activation and form IKs. The IKs in serum reflects the amount of complement activation.
- 6. Causes of autoimmune disease • Molecular Mimicry (Cross reacting antigen) • Molecular mimicry or sharing of epitopes between an infectious agents or parasites and body tissue specific antigen results in autoimmunity and tissue damage. • Example: Trypanosoma cruzi contain antigen that cross react with mammalian neurons and heart muscle results in nervous and heart disease. Rheumatic fever is an inflammatory autoimmune disease that may develop after an infection with group A Streptococcus bacteria (such as strep throat or scarlet fever). The disease can affect the heart, joints, skin, and brain.
- 7. Some common autoimmune disease • 80 or more different autoimmune diseases. • long-term illnesses, with the severity of symptoms changing over time. • Some common autoimmune diseases include: • diabetes mellitus type 1 (IDDM), • systemic lupus erythematosus (SLE), • Hashimoto's thyroiditis, • Graves' disease of the thyroid, • Sjogren's syndrome, • Churg-Strauss Syndrome, • rheumatoid arthritis (RA),
- 8. Type 1 diabetes mellitus • Immune system antibodies attack and destroy insulin-producing cells in the pancreas. • By young adulthood, people with type 1 diabetes require insulin injections to survive.
- 9. Systemic lupus erythematosus (SLE) • People with lupus develop autoimmune antibodies that can attach to tissues throughout the body. The joints, lungs, blood cells, nerves, and kidneys are commonly affected in lupus.
- 10. Hashimoto’s disease • Hashimoto’s disease is an autoimmune disorder that can cause hypothyroidism, or underactive thyroid. • With this disease, the immune system attacks thyroid. The thyroid becomes damaged and can’t make enough thyroid hormones.
- 12. Graves' disease of the thyroid
- 13. Sjogren's syndrome • Sjogren's (SHOW-grins) syndrome is a disorder of immune system identified by its two most common symptoms — dry eyes and a dry mouth.
- 14. Churg-Strauss syndrome • is one of many forms of vasculitis. • Vasculitis diseases are characterized by inflammation of blood vessels. • Churg-Strauss syndrome, in particular, occurs in patients with a history of asthma or allergy and features inflammation of blood vessels (also referred to as angiitis) in the lungs, skin, nerves, and abdomen. The blood vessels involved in Churg-Strauss syndrome are small arteries and veins.